Staphylococcus aureus skin colonization in atopic dermatitis children is associated with decreased IFN‐ γ production by peripheral blood CD4 + and CD8 + T cells

Atopic dermatitis (AD) is a chronic inflammatory skin disorder, which is associated with an increased expression of Th2 cytokines with concomitant decrease in IFN‐ γ production by circulating CD4 + and CD8 + T cells. The skin of patients with AD is often colonized by Staphylococcus aureus , which may reflect in changes in immunological parameters. The aim of the study was flow cytometric measurement of some peripheral blood lymphocyte subsets expressing naive/memory marker (RA/RO) and activation marker (CD25) as well as intracellular production of IFN‐ γ by peripheral blood CD4 + and CD8 + T cells from varied severity AD children and determine the impact of S. aureus skin colonization on cytokines profiles. There was a significant increase in the percentage of CD4 + and CD8 + T cells producing IL‐4 and IL‐13 and decrease in the percentage of CD4 + and CD8 + T cells producing IFN‐ γ upon in vitro stimulation with phorbol 12‐myristate 13‐acetate and ionomycin in children with AD compared to healthy ones. The absolute number of CD4 + and CD8 + T cells expressing memory marker CD45RO was elevated as compared with controls. The severity of AD was positively correlated with the percentage of lymphocyte subsets: CD45RO + , CD4 + CD45RO + , and the percentage of CD3 + and CD4 + expressing CD25 as well as the number of S. aureus on the skin. In conclusion, both CD4 + and CD8 + memory T cells are involved in the immunopathogenesis of AD. S. aureus skin colonization is related with disease severity and changes in expression of CD45RO and CD25 on T cells. A decrease in the percentage of CD4 + and CD8 + T cells producing IFN‐ γ in AD children may explain propensity for skin infection.